A wheel surprise: Reaction of resorcinol and 1,5‐pentanedial in ethanol at 80 °C for 48 h in the presence of HCl surprisingly afforded a soluble cyclic oligomer in high yield (83 %) under thermodynamic control. Single‐crystal X‐ray analysis revealed a waterwheel‐like structure with a large hydrophobic hole through the center (see picture). A carboxylic ester derivative of the compound was shown to be highly selective for Rb+ ions.

Paneth cell metaplasia is a non-specific phenomenon in the proximal colon, but distal PCM, which occurs exclusively in affected mucosa, is a useful marker indicating IBD, even in the inactive phase. Regression analysis suggests that repair and regeneration may be the most potent stimuli causing PCM.

The results suggest that epithelial apoptosis is a non-specific phenomenon and that an increased number of apoptotic cells exceeding histiocyte phagocytic capacity may play a part in the disruption of epithelial defenses and further accelerate mucosal inflammation.

The ring-expansion reaction of equimolar cyclic dithioester 1 with 3-phenoxypropyrene sulfide (PPS) (cyclic dithioester 1/PPS ) 1/2) was examined in the presence of TBAC as a catalyst in NMP for 24 h. It was found that intermolecular ester-exchange reaction occurred during the insertion reaction of PPS into cyclic dithioesters, and cyclic polymers with M ns ) 3600-8900 were obtained in 80-96% yields. The structures of the obtained cyclic polymers were confirmed by the 1 H NMR, 13 C NMR IR, and MALDI TOF-MS spectroscopy. The continuous insertion reaction of excess PPS into cyclic dithioester (cyclic dithioester 1/PPS ) 1 /50) was also examined, and it was found that the insertion reaction proceeded quantitatively to afford the corresponding cyclic polysulfide with M n ) 42 000 and Mw/Mn ) 4.50 in a 96% yield.

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